Jan 17, 2021The fact is, radio technology is inherently unreliable. When several wireless technologies share the same radio band and multiple devices are communicating across it, interference is inevitable. Collisions between data packets can occur. But the unreliability of radio doesn't equate to the unreliability of wireless communication systems—even in noisy environments, like those within commercial and industrial Internet of Things (IoT) settings.
In these settings, reliability is critical. The connectivity of smart factories, buildings, management systems, hospitals and entire supply chains depends on it. To ensure the level of reliability needed for these environments, wireless technologies must have features in place that lower the probability of collisions and offset inevitable packet loss. Overcoming interference and achieving highly reliable wireless connectivity is possible with the right wireless backbone and mitigation techniques. Making the unreliable reliable is essential as we move into the next frontier of smart industry and smart building development.
How Bluetooth Technology Overcomes Interference
Unlike wired data communications technologies, wireless technologies must share a transmission medium. For example, Bluetooth technology operates in the same 2.4 GHz ISM frequency band as Wi-Fi and technologies that use the IEEE 802.15.4 standard. Collisions can occur when multiple devices communicate data across the same frequency channel at the exact same time. To overcome this challenge, wireless technologies have to take a multi-pronged approach. Bluetooth technology has adopted four key techniques to reduce interference and increase its reliability to the level needed in many IoT applications.
Small, Fast Packets
The less airtime a packet endures and the less space it takes up, the lower the probability of collision. For this reason, it's best for data packets to be small and fast. Bluetooth Low Energy (BLE) packets are typically half the size and four times faster than other low-power wireless mesh networking technologies. This helps them travel through crowded environments with fewer collisions and use the spectrum more efficiently.
Adaptive Frequency Hopping
Avoiding conflict is key to a highly reliable connection. To find a clear transmission path, Bluetooth technology uses a form of frequency-hopping spread spectrum (FHSS) called adaptive frequency hopping (AFH). Like all FHSS technologies, Bluetooth technology divides the frequency band into smaller channels. In the case of BLE, the band is split into 40 channels and Bluetooth packets rapidly hop between those channels when being transmitted. To further reduce the chance of interference, Bluetooth technology adapts its hopping sequence. Channels that are noisy and busy are dynamically tracked and avoided when packets are sent.
Acknowledgements
Even with mitigation techniques, some level of packet loss is inevitable. One technique Bluetooth technology uses to compensate for packet loss is sending acknowledgements, allowing receiving devices to confirm the successful receipt of data from the sender. Acknowledgements are a technique available for Bluetooth point-to-point (packet acknowledgement) and mesh networking (message acknowledgement) connections.
Automatic Retransmission
Relying on acknowledgements is not always practical. Imagine if a single light switch controlling 100 lights in a manufacturing plant had to wait for and track 100 acknowledgements every time it sent an on/off message. To combat this challenge, Bluetooth technology includes a retransmission feature that automatically sends multiple copies of a message in rapid succession. Automatic, rapid retransmission of mesh messages dramatically increases the probability of successful receipt between connected devices.
Industrial and Commercial IoT Applications with Reliable Connectivity
Wireless communications systems are an integral component of the industrial and commercial IoT, providing connectivity and streamlining business operations across facilities and equipment. With so much depending on these systems, developers should prioritize a connectivity technology built to combat interference and improve reliability. Let's take a closer look at three key IoT applications that require enhanced reliability, and how Bluetooth interference mitigation plays a role.
Asset Tracking
Asset tracking is one application for which reliable data transmission in dynamic environments is crucial. For instance, logistics tracking in warehouses ensures that inventory and shipments are accounted for, thus preventing loss. And asset tracking in the healthcare industry enables life-saving materials like vaccines and medications to be tracked and traced in real time through the pharmaceutical supply chain. In these applications, for which there is an elevated need for accuracy, the reliability techniques above can work in tandem with features like Bluetooth direction finding to create robust, wireless communication capable of centimeter-level precision.
Condition Monitoring
Another wireless application that requires a high level of reliability is condition monitoring. When deployed at scale across a facility, sensor networks can monitor system performance in real time, avoiding equipment downtime and improving production efficiency. Bluetooth technology tracks the sequence of data being transmitted and received in these applications and uses data retransmissions to reduce the likelihood of errors. Because condition monitoring is often applied in complex environments like manufacturing, transportation and smart buildings, adaptive frequency hopping is particularly effective in avoiding noisy channels and limiting interference.
Building Automation
For building automation systems, including lighting, HVAC, and security, efficiency and reliability are two of the biggest needs. Take connected lighting as an example. A single Bluetooth mesh network may connect hundreds or even thousands of lighting devices, which require virtually instant responsiveness. This is why small, fast data packets are essential to reducing latency, keeping channels clear and preventing network saturation. In other words, packet speed not only improves the operation of these applications but plays a critical role in ensuring their reliability.
The Future of a Reliable IoT
Wireless connectivity is powering the next generation of smart facilities, keeping processes in tune, while driving new levels of efficiency, productivity and cost savings. The Bluetooth Special Interest Group (SIG) predicts that 892 million Bluetooth network devices and 538 million Bluetooth location services devices will be shipped annually by 2024, illustrating the growing role of wireless technologies in the Internet of Things.
With proper solutions and features in place, radio's inherent reliability isn't insurmountable. Wireless technologies can provide highly reliable communication in the most challenging settings, opening up opportunities for developers to capitalize on commercial and industrial IoT applications in ways they never have before.
Jim Katsandres leads the Developer Relations activities at the Bluetooth SIG. His international team works to provide developers with the information and resources they need to create the next generation of Bluetooth-enabled products and services. Katsandres has been in the IoT, cloud and device space for more than 25 years, working within platform technology, software-as-a-service, embedded original equipment manufacturer, systems integrator, independent software vendor and consulting organizations.
